1. Field of the Invention
The present invention relates to an image formation apparatus provided with a locking mechanism to lock a first housing and a second housing.
2. Related Background Art
Traditionally, a facsimile apparatus is structured with a main body frame which serves to be a nucleus to fabricate the apparatus wholly by combining three parts, an upper cover, a lower cover, and the main frame as disclosed in U.S. Pat. No. 4,768,100 and others.
Also, recently, there has been disclosed an apparatus structured with two parts, an integrated body of the main frame and the lower cover and the upper cover which is incorporated therewith, to fabricate the apparatus wholly such as described in U.S. patent application Ser. No. 07/710,836 filed on Jun. 5, 1991.
In a facsimile apparatus and the like, a main body 100 of the apparatus and a cover 101 are structured to be capable of being opened and closed as shown in FIG. 19 for the performance of the recording sheet replacement or a jam disposition. In this case, recording cannot be performed while the cover 101 is in a state of being opened. Traditionally, therefore, the structure is arranged to lock the main body of the apparatus 100 and its cover 101 in a state that they are closed by hooking the locking nail 103 of the cover 101 to the locking shaft 102 of the main body 100 and at the same time, a sensor 104 is provided for the main body 100 to detect the open-close state of the cover 101.
In other words, when the cover 101 is closed, the cover 101 depresses an actuator 104a to turn on the sensor 104, and when the cover 101 is opened, pressure on the aforesaid actuator 104a is released to turn off the sensor 104.
However, in the aforesaid structure, while there is no problem when the cover 101 is opened or closed definitely or there is no bend or the like on the cover 101, the sensor 104 may be turned on because the actuator 104a is depressed by the cover 101 even when the cover 101 is closed with an imperfect locking if there is a bend or the like on the cover 101. On the contrary, even if the locking is perfect, the actuator 104a is not depressed depending on the states of the cover 101 to allow the sensor 104 to remain in its off-state, or some other malfunctions may result.
Also, in an apparatus such as this, a recording head is installed on the cover side while a platen roller is provided on the main body side of the apparatus, and the structure is arranged so that both of them are in contact under pressure when the cover is closed. To this end, coil springs are provided between the recording head and the ceiling plane inside the cover to cause the recording head to compress the platen roller by the biasing force of the aforesaid springs.
Nevertheless, because the cover of the aforesaid apparatus is generally made of plastic resin, the cover tends to bend by being pressed from its inner ceiling by the reaction of the coil springs when the cover is closed. Then, if the cover is bent, it becomes difficult to set the compression force of the head accurately. Traditionally, therefore, a metal plate is affixed to the ceiling plane inside the cover to receive the pressure of the coil springs by this metal plate.
In the aforesaid structure, the metal plate should be affixed to the ceiling plane inside the cover in order to receive the pressure of the coil springs, which leads to an increase in the number of parts as well as in the number of assembling processes. Moreover, there is a problem that the installation of the metal plate on the ceiling plane inside the cover tends to allow noises at the time of recording to produce resonance in the apparatus to amplify the noises.